unable to view itune movie

altho i have had a mac and iphone and ipod for years i have never bought a movie. now recovering from an african illness idecided to buy some old westerns to watch. however i cant do so as there is a grey panel over the viewing are. im sure this is a ridiculously simple problem but cant seem to fix it. Help please

NOTE: Thread moved to appropriate forum. Not just anything goes in Anything Goes